/**
 * ***************************************************************************** Copyright (c) 2003,
 * 2006 Subclipse project and others. All rights reserved. This program and the accompanying
 * materials are made available under the terms of the Eclipse Public License v1.0 which accompanies
 * this distribution, and is available at http://www.eclipse.org/legal/epl-v10.html
 *
 * <p>Contributors: Subclipse project committers - initial API and implementation
 * ****************************************************************************
 */
package org.tigris.subversion.subclipse.core.util;

/**
 * <code>Assert</code> is useful for for embedding runtime sanity checks in code. The predicate
 * methods all test a condition and throw some type of unchecked exception if the condition does not
 * hold.
 *
 * <p>Assertion failure exceptions, like most runtime exceptions, are thrown when something is
 * misbehaving. Assertion failures are invariably unspecified behavior; consequently, clients should
 * never rely on these being thrown (and certainly should not being catching them specifically).
 */
public final class Assert {
  /* This class is not intended to be instantiated. */
  private Assert() {}
  /**
   * Asserts that an argument is legal. If the given boolean is not <code>true</code>, an <code>
   * IllegalArgumentException</code> is thrown.
   *
   * @param expression the outcode of the check
   * @return <code>true</code> if the check passes (does not return if the check fails)
   * @exception IllegalArgumentException if the legality test failed
   */
  public static boolean isLegal(boolean expression) {
    return isLegal(expression, ""); // $NON-NLS-1$
  }
  /**
   * Asserts that an argument is legal. If the given boolean is not <code>true</code>, an <code>
   * IllegalArgumentException</code> is thrown. The given message is included in that exception, to
   * aid debugging.
   *
   * @param expression the outcode of the check
   * @param message the message to include in the exception
   * @return <code>true</code> if the check passes (does not return if the check fails)
   * @exception IllegalArgumentException if the legality test failed
   */
  public static boolean isLegal(boolean expression, String message) {
    if (!expression) throw new IllegalArgumentException(message);
    return expression;
  }
  /**
   * Asserts that the given object is not <code>null</code>. If this is not the case, some kind of
   * unchecked exception is thrown.
   *
   * @param object the value to test
   * @exception IllegalArgumentException if the object is <code>null</code>
   */
  public static void isNotNull(Object object) {
    isNotNull(object, ""); // $NON-NLS-1$
  }
  /**
   * Asserts that the given object is not <code>null</code>. If this is not the case, some kind of
   * unchecked exception is thrown. The given message is included in that exception, to aid
   * debugging.
   *
   * @param object the value to test
   * @param message the message to include in the exception
   * @exception IllegalArgumentException if the object is <code>null</code>
   */
  public static void isNotNull(Object object, String message) {
    if (object == null)
      throw new AssertionFailedException("null argument:" + message); // $NON-NLS-1$
  }
  /**
   * Asserts that the given boolean is <code>true</code>. If this is not the case, some kind of
   * unchecked exception is thrown.
   *
   * @param expression the outcode of the check
   * @return <code>true</code> if the check passes (does not return if the check fails)
   */
  public static boolean isTrue(boolean expression) {
    return isTrue(expression, ""); // $NON-NLS-1$
  }
  /**
   * Asserts that the given boolean is <code>true</code>. If this is not the case, some kind of
   * unchecked exception is thrown. The given message is included in that exception, to aid
   * debugging.
   *
   * @param expression the outcode of the check
   * @param message the message to include in the exception
   * @return <code>true</code> if the check passes (does not return if the check fails)
   */
  public static boolean isTrue(boolean expression, String message) {
    if (!expression)
      throw new AssertionFailedException("assertion failed: " + message); // $NON-NLS-1$
    return expression;
  }
}
